My brother-in-law bought a Ford diesel shortbed and wants to tow a 30ft 5th wheel. (He says his first preference was a RAM diesel but he gets a big Ford employee discount and could not pass it up). Anyway, he has been told that he can only haul the 5th wheel if he uses a "sliding hitch". Is this true? If not, what are the pros & cons of not having a sliding hitch. Thanks !